Cabinet having heat exchanger integrally installed between roof and solar shield

ABSTRACT

A cabinet has an inner roof portion and an outer roof portion above the inner roof portion. A solar shield is above the outer roof portion. A heat exchanger has a first portion that absorbs heat. The first portion of the heat exchanger is located between the inner roof portion and the outer roof portion. The heat exchanger has a second portion that rejects heat. The second portion of the heat exchanger is located between the outer roof portion and the solar shield. The heat exchanger has a heat pipe for transferring heat between the first passage and the second passage. The heat pipe includes an evaporator that absorbs heat from the heated air and a condenser that rejects heat to the cooled air.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from co-pending Provisional Application Serial No. 60/332,458 filed Nov. 21, 2001, and entitled CABINET HAVING HEAT EXCHANGER INTEGRALLY INSTALLED BETWEEN ROOF AND SOLAR SHIELD.

FIELD OF THE INVENTION

[0002] The present invention relates to thermal control systems generally, and in particular to cooling systems for equipment cabinets.

BACKGROUND OF THE INVENTION

[0003] Most cabinet cooling systems use a side mounted or internally mounted heat exchanger. These applications create either an obtrusive element hanging on the outside of the cabinet or consume considerable area within the enclosure.

[0004] PCT International Publication No. WO 09708795 describes a switchgear cabinet with a heat exchanger which is built into a side wall, and has an internal circuit and an external circuit. An integral heat sink is built into an opening in the side wall. The integral heat sink has vertical inner cooling ribs projecting into the interior of the switchgear cabinet and vertical outer cooling ribs lying on the cabinet exterior. An inner fan draws air out of the cabinet interior and, in the upper region, feeds it to the inner ducts which are formed between the inner cooling ribs and in which the air drawn in is guided into the lower region of the inner ducts and from there out into the cabinet interior.

[0005] An improved cabinet is desired.

SUMMARY OF THE INVENTION

[0006] One aspect of the invention is a heat exchanger, comprising first surfaces defining a first passage for transmitting heated air and second surfaces defining a second passage for transmitting cooling air that has a lower temperature than the heated air. Heat pipe means transfer heat between the first passage and the second passage. The heat pipe means include an evaporator that absorbs heat from the heated air and a condenser that rejects heat to the cooling air.

[0007] Another aspect of the invention is a cabinet assembly. A cabinet has an inner housing and an outer housing outside the inner housing. A heat shield is outside the outer housing. A heat exchanger has a first portion that absorbs heat. The first portion of the heat exchanger is located between the inner housing and the outer housing. The heat exchanger has a second portion that rejects heat. The second portion of the heat exchanger is located between the outer housing and the heat shield.

[0008] Another aspect of the invention is a cabinet having an inner roof portion and an outer roof portion above the inner roof portion. A solar shield is above the outer roof portion. A heat exchanger has a first portion that absorbs heat. The first portion of the heat exchanger is located between the inner roof portion and the outer roof portion. The heat exchanger has a second portion that rejects heat. The second portion of the heat exchanger is located between the outer roof portion and the solar shield.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a diagram showing an exemplary cabinet assembly according to the present invention.

[0010]FIG. 2 is a diagram of a variation of the assembly of FIG. 1, having a different heat exchanger.

DETAILED DESCRIPTION

[0011]FIG. 1 is a diagram showing an exemplary cabinet assembly 100 according to the invention. The cabinet assembly 100 includes a cabinet having an inner roof portion 114 and an outer roof portion 118 above the inner roof portion. A heat shield 120, which may be a solar shield lies above the outer roof portion 118.

[0012] A heat exchanger 131 has an inner flow passage 164 between inner roof portion 114 and outer roof portion 118, and an outer flow passage 162 between outer roof portion 118 and solar shield 120. Heat exchanger 131 also includes a heat pipe assembly 130 having a first portion 130 a that absorbs heat. The first portion 130 a of the heat pipe assembly 130 is located between the inner roof portion 114 and the outer roof portion 118. The heat pipe assembly 130 has a second portion 130 b that rejects heat. The second portion 130 b of the heat pipe assembly 130 is located between the outer roof portion 118 and the solar shield 120.

[0013] The cabinet has an inner housing 111 that includes the inner roof portion 114. The cabinet has an outer housing 110 that includes the outer roof portion 118. The cabinet assembly 100 has an air circulation path 119 that passes over the first portion 130 a of the heat pipe assembly 130. The air circulation path 119 includes a space between the inner housing 114 and the outer housing 118. The cabinet may be formed of any convenient materials, such as steel or aluminum. The housing walls 110 and 111, racks 150-153, and fans 142, 140, 144, and 146-149 may be of conventional design.

[0014] The positions of the various fans may be varied as desired. Although the exemplary embodiments include fans 146-149 below respective racks 150-153, the fans could be above the racks. Fan 140 could be positioned to the left or right of heat pipe assembly 130. Fan 144 could be positioned to the left or right of heat pipe assembly 130.

[0015] As shown in FIG. 1, the flow of cold air F_(C) is blown by blower 142 and fans 146-149 through racks 150-153, wherein the air absorbs heat from the racks 150-153 and the various equipment (not shown) therein. Although the exemplary fan trays 146-149 each have three fans, any number of fans may be included in each fan tray. The flow of hot air F_(H) is then blown by a fan 140 across the evaporator sections 136 of the heat pipes 132. The heat pipes 132 absorb the heat from the hot air flow F_(H). A first plurality of fins or plates 135 a connected to the evaporators 136 of heat pipes 132 provide additional surface area for convection heat transfer from the air flow F_(H) to the heat pipes 132. A second plurality of fins or plates 135 b connected to the heat pipes 132 provide additional surface area for convection heat transfer from the condensers 134 of the heat pipes 132 to ambient air flow F_(A). The fins 135 may be attached to the heat pipes by a compression fit, soldering, conductive adhesive or other known method of providing mechanical and conductive coupling.

[0016] Although the exemplary cabinet assembly includes a single fan 140 adjacent to the heat exchanger 140, and a single blower 142 at the bottom of the cabinet, any number of fans or blowers may be used to achieve a desired flow rate and cooling capacity.

[0017] The exemplary heat pipe assembly 130 includes at least one heat pipe 132 having an evaporator 136 in the heated flow F_(H) between the inner housing 114 and the outer housing 118, and a condenser in the cooler ambient air flow F_(A) between the outer housing 118 and the solar shield 120. One or more fans 144 blow ambient air F_(A) over the condensers 134 in the space between the outer roof 118 and the solar shield 120. The exemplary heat exchanger has a plurality of such heat pipes 132. Advantageously, the heat pipes 132 are passive devices. In addition, the heat pipes 132 can reject a large amount of heat with a small temperature differential between the evaporators 136 and the condensers 134. Thus, the exemplary cabinet can maintain the temperature of the chilled air flow F_(C) close to the temperature of the ambient air flow F_(A). In addition, if the cabinet 100 always remains positioned with the condensers 134 above the evaporators 136 in a terrestrial environment (i.e., subject to gravity), then heat pipes 132 may be replaced by thermosyphons, making wicks optional.

[0018] In a variation of the example of FIG. 1, the shield 120 may be located on another surface of the cabinet (e.g., a side wall) with the heat exchanger 131 on the side of the cabinet 100. In this case, the evaporator section 130 a is between the inner side wall 112 and the outer side wall 116 of cabinet 100, and the condenser section 130 b is between the outer side wall 116 and the shield 120. It will be understood that any heat pipes 132 used on the side of the cabinet in this manner include a wick, to return condensed liquid working fluid to the evaporator section of each heat pipe by capillary pumping action.

[0019] Although the exemplary shield 120 is a solar shield, other types of heat shields may be used. For example, the heat shield 120 may be a shield for heat from any radiant heat source. Preferably, the heat shield 120 has an outer surface with a high ratio of absorptivity to emissivity. Preferably, the heat shield 120 has an insulating core to prevent transfer of the solar heat from the top of heat shield 120 to the ambient air flow F_(A).

[0020] The heat exchanger 131 is integrated into the cabinet construction. Further, the external loop 162 of the heat exchanger 131 uses the space between the cabinet roof 118 and the solar shield. This advantage may be realized using other types of heat exchangers than the example described above. Although the heat pipe means 130 of FIG. 1 uses cylindrical heat pipes, other types of heat pipe means may be used. For example, FIG. 2 shows a variation in which the heat pipe means 230 have a flat vapor chamber 232 mounted in the top roof panel 118. The bottom face 234 of vapor chamber 230 acts as an evaporator and the top face 236 acts as a condenser. Fins 238 may be provided above the top face 236 to dissipate heat, and fins 239 may be provided below the bottom face 234 to absorb heat from the heated air flow F_(H) in passage 264. Although fins 238 and 239 are shown as plate fins, other types of fins (e.g., pins, folded fin or the like) may be used.

[0021] Other types of heat exchangers known to those of ordinary skill in the art may be used.

[0022] Although the invention has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly, to include other variants and embodiments of the invention which may be obvious to those skilled in the art without departing from the scope and range of equivalents of the invention. 

What is claimed is:
 1. A cabinet assembly comprising: a cabinet having an inner housing nested within an outer housing; a heat shield positioned outside said outer housing; and a heat exchanger having a first portion that absorbs heat, said first portion of said heat exchanger being located between said inner housing and said outer housing, said heat exchanger having a second portion that rejects heat, said second portion of said heat exchanger being located between said outer housing and said heat shield.
 2. A cabinet assembly according to claim 1 further including an air circulation path within said cabinet that passes over said first portion of said heat exchanger, wherein said air circulation path includes a space between said inner housing and said outer housing.
 3. A cabinet assembly according to claim 1 wherein said heat exchanger includes at least one heat pipe having an evaporator between said inner housing and said outer housing, and a condenser between said outer housing and said heat shield.
 4. A cabinet assembly according to claim 1 wherein said heat exchanger includes a plurality of heat pipes, each having an evaporator between said inner housing and said outer housing, each having a condenser between said outer housing and said heat shield.
 5. A cabinet assembly according to claim 2 further comprising one or more racks, wherein said air circulation path passes through said one or more racks wherein at least one of said one or more racks has a fan that circulates air in a direction of said air circulation path.
 6. A cabinet assembly according to claim 1 further comprising a plurality of equipment racks within said inner housing, and one or more fans located between pairs of said equipment racks.
 7. A cabinet assembly comprising: a cabinet having an inner roof portion and an outer roof portion located above said inner roof portion; a solar shield located above said outer roof portion; a heat exchanger having a first portion that absorbs heat, said first portion of said heat exchanger being located between said inner roof portion and said outer roof portion, said heat exchanger having a second portion that rejects heat, said second portion of said heat exchanger being located between said outer roof portion and said solar shield; and an air circulation path that passes over said first portion of said heat exchanger.
 8. A cabinet assembly according to claim 7 wherein said cabinet has an inner housing that includes said inner roof portion, said cabinet has an outer housing that includes said outer roof portion, and said air circulation path includes a space between said inner housing and said outer housing.
 9. A cabinet assembly according to claim 7 wherein said heat exchanger includes at least one heat pipe having an evaporator between said inner housing and said outer housing, and a condenser between said outer housing and said solar shield.
 10. A cabinet assembly according to claim 7 wherein said heat exchanger includes a plurality of heat pipes, each having an evaporator between said inner housing and said outer housing, each having a condenser between said outer housing and said solar shield, and further comprising one or more racks, wherein said air circulation path passes through said one or more racks.
 11. A cabinet assembly according to claim 10 wherein at least one of said one or more racks has a fan that circulates air in a direction of said air circulation path.
 12. A cabinet assembly according to claim 11 comprising: a plurality of equipment racks within said inner housing, and one or more fans located between each of a consecutive pair of equipment racks in said plurality of equipment racks.
 13. A cabinet assembly according to claim 12 wherein said heat exchanger includes at least one heat pipe having an evaporator between said inner roof portion and said outer roof portion, and a condenser between said outer roof portion and said solar shield; and wherein said heat exchanger includes a plurality of heat pipes, each having (i) an evaporator between said inner roof portion and said outer roof portion, and (ii) a condenser between said outer roof portion and said solar shield.
 14. A heat exchanger, comprising: first surfaces defining a first passage for transmitting heated air; second surfaces defining a second passage for transmitting cooling air that has a lower temperature than said heated air; and at least one means for transferring heat between said first passage and said second passage, said heat transferring means including an evaporator that absorbs heat from said heated air and a condenser that rejects heat to said cooling air; and wherein said heat transferring means comprise at least one cylindrical heat pipe having an evaporator that projects into said first passage, and a condenser that projects into said second passage; a first plurality of fins located in said first passage and thermally coupled to said evaporator; and a second plurality of fins located in said second passage and thermally coupled to said condenser.
 15. A heat exchanger according to claim 14 wherein said first surfaces include an exterior surface of an outer wall of a cabinet; and said second surfaces include an interior surface of a solar shield outside of said cabinet. 